Carding machines are well known textile machines whose function is to form, starting from disorderly fibers, a thin veil whose fibers are orientated in the direction of their movement in the machine.
This veil is, in certain processes such as those referred to as combed and semi-combed processes, collected in a metal sheet that is in the shape of a funnel to form a ribbon or a wick, whose width is clearly less than that of the veil.
This wick is then, in a classical process well known to those skilled in the art, usually placed in large capacity cylindrical drums by means of a feeding head or feeder.
The wick is placed in a drum being filled by an encircularly moving feeding head, the diameter of whose movements is slightly less than the internal radius of the drum. The circle defined by the movement of the feeding head is very nearly internally tangential to the surface of the drum, in such a way that a small cylindrical portion in the center of the drum remains free from wick. Additionally, the drum is itself moved with a slow movement of rotation.
The wick is therefore deposited in the drum in the form of loops, or successive spirals with each spiral being slightly shifted in relation to the preceeding spiral. These spirals progressively cover the whole periphery of the drum. Then, when the last spiral has performed a complete round, a second layer is deposited, and so on.
During the filling of the drum, another empty drum is waiting, positioned, for example, to the right of the drum being filled. Known means, such as guide rollers are provided to move the drums from the right to the left.
One of the problems encountered during this process is that carding machines have a larger inertia, and are not able to be quickly started or stopped. Thus, any stoppage of the carding machine results in a waste of time, and, thereby an important loss of production.
When the drum in which the wick is deposited is filled, it must be removed and replaced by another drum. For the reason described above, this changing of the drum must take place while the carding machine is operating. The carding machine therefore continues to deliver the wick at the working speed, even though there may not be a drum in place to receive said wick.
The changing of the drum necessitates the presence of a worker when the drum being filled reaches its filling point. This changing of the drum takes a certain amount of time. During this time the wick delivered by the carding machine is deposited on the ground between the filled drum and the new empty drum.
In an attempt to alleviate these disadvantages, systems have been developed in which the changing of the drum is automatically effectuated without the intervention of an operator. In these systems, the filled drum is removed from the feeding head and, simultaneously, an empty drum is positioned in the place from which the filled drum has just been removed.
Unfortunately, no matter how rapidly it is performed, this operation still takes a period of time to complete. Thus, despite the advantages offered by these systems, the changing of the drums can not occur without a certain length of the wick being deposited on the ground between the filled drum and the empty drum.
Another problem encountered by these systems involves severing of the wick once a drum has been filled. If, once a drum has been filled, the wick is not severed, then the rotation of the new drum, exposed the wick coming from the filled drum to becoming "caught" in the process of wick being deposited in the new drum. In such an event, a part of the wick contained in the filled drum becomes unwound and spills out of this filled drum. Additionally, if the part of the wick which has fallen between the two drums is too long, it can get caught in the automatic drum changing mechanism or in the wheels of the drums, which could cause other problems, including losses of time for the operator.
Thus, despite the advantages offered by these systems, an intervention from the operator is then still necessary to break (sever) the wick between the two drums, thereby totally dissociating these two drums. Also, this operation of breaking the wick by the operator keeps the automatic drum changing system from being completely automatic, since a manual operation persists.
All the problems described above are increased by the fact that modern carding machines deliver the wick with an ever increasing linear speed. In this regard, it must be noted that at the elevated process speeds presently practiced --that is, speeds of 400 m/min.--a change of the drum in 3 seconds results in about a fifth of the wick delivered in that time --that is, about 4 meters of wick--falling on the ground between the two drums. Moreover, if the wick is not sectioned immediately, the feeding in the new drum draws not only the wick coming from the feeding head, but also the wick that has already deposited in the old drum, which then will have a tendency to empty itself. Thus, the drums must be changed more and more frequently, even though drum capacity has been increased by an increasing diameter.
Therefore, the operator is required more and more, while a totally automated system would free him from these tasks, allowing him to perform other duties.
Finally, systems have been proposed to avoid the inconveniences described above by automatically breaking the wick between the filled drum and the empty drum and by receiving the wick delivered while the drum changing is taking place. However, these systems are not adapted to the high feeding speeds that are utilized today, for example in the field of the semi-combed processes wherein the wick is fed at speeds reaching 400 m/min. Accordingly, these systems result in a large amount of wick being received on a table and in the subsequent placement in the drum of these large amounts of unwound wick, usually while the drum is being fed additional wick by the feeding head. Such an arrangement results in uneven filling of the drums which wastes storage space and can pose potential problems with knotting of the fibers.